Their playoff hopes may hinge on it.
One day after Collie lay motionless on the field for nearly 10 minutes, coach Jim Caldwell said Monday that the second-year receiver returned to Indianapolis on the team flight and was recovering from a concussion.
"Obviously the doctors felt good enough about his situation to allow him to travel back with us on the airplane," Caldwell said. "I think that's a pretty good indication that things were trending in the right direction. He came back, he was home sleeping, our medical staff had an opportunity to talk with him this morning and his symptoms are subsiding. He's trending in the right direction, which is great."
Fortunately, Collie appears to have escaped a more serious injury after Sunday's frightening scene in Philadelphia.
The contact on Collie was initiated by Eagles safety Quintin Mikell, who delivered a legal hit with his shoulder to the chest area of Collie. That contact propelled Collie toward Eagles safety Kurt Coleman, causing Coleman to make helmet-to-helmet contact with Collie, who crumpled to the turf with his two arms frozen in the air.
Collie was strapped to a backboard and taken off the field on a stretcher.
NFL Network insider Jason La Canfora reports that because the helmet-to-helmet contact was a result of Collie being driven toward Coleman by Mikell's legal hit, the NFL will not impose a fine on Coleman.
"You definitely want to pray in that situation so that it's not bad as it looks," defensive captain Gary Brackett said. "And for that moment, it really puts things in perspective."
And after the game, Collie could be seen walking around the locker room though he did not take reporters' questions.
Teammates were relieved with what they saw and heard.
"Austin is one of my best friends on this team and it's tough to watch. It's tough," tight end Jacob Tamme said. "We just tried to focus on football, but it's definitely tough. It was good to get to talk to him (on the plane), and he's going to be good -- we hope."
But the latest injury is yet another blow for the defending AFC champs.
Twelve players have already gone on injured reserve, and that list doesn't even include oft-injured safety Bob Sanders, who tore the biceps muscle in his right arm in the season opener and hasn't played since. Colts President Bill Polian said last week he hoped Sanders would return next month.
And the injury rash just seems to be getting worse.
At one point Sunday, all three of Indy's opening-day linebackers were on the sideline -- Gary Brackett, Philip Wheeler and Clint Session.
The usually high-powered offense hasn't been immune, either.
Manning has already lost All-Pro tight end Dallas Clark (wrist) for the season and has played the last two games without Joseph Addai (left shoulder). The four-man receiving corps that was expected to the deepest and most talented of the Manning era, has played together once all season, and even Polian said Saturday that while the team mantra is next man up, he's not even sure who the next man is.
"I don't think we've really changed anything about this offense," Tamme said. "That's really the neat thing about this team, we understand what we're supposed to do and just go out there and go to work."
The Colts gave their players an unscheduled day off Monday, presumably to let them get an extra day to heal.
They need it.
Addai, third-string running back Mike Hart (ankle) and Session didn't even make the trip to Philly. Brackett and Wheeler both left the game briefly in the second half, and, now Collie, who just returned from thumb surgery, will be back on the injury report.
New NFL rules on concussions will require Collie to take a baseline neurological test and have his answers compared with the ones he gave before the season. He also has to be cleared by team doctors and an independent neurological specialist before he can get back in pads.
"They can make a determination of where he is," Caldwell said. "He'll be released to play whenever he is cleared."
"I think it was great even to be able to relay the news that, 'Hey, he is fine. He's alert,' even prior to the game being finished," Caldwell said. "That certainly lifted a lot of spirits, in that regard.
"He is a guy that can come back and do his job," Caldwell added. "We fully anticipate that he will have the same fervor and fire in terms of his preparation in terms of trying to overcome this setback."
The Associated Press contributed to this report.